4.2 Nerves CTD Flashcards
What is a nerve plexus? Why are they important?
– interlacing nerve networks grouped by body regions
Blending of nerve fibers from the ventral rami from adjacent spinal nerves
Purpose: areas receive nerve supply from more than one spinal nerve
limits the loss of complete region if a nerve is damaged
What do nerve plexuses attach to?
Ventral rami of spinal nerves
What are the nerve plexuses? Where are they?
Cervical Plexus (C1-C4) Brachial Plexus (C5 – T1) Lumbar Plexus (L1-L5) Sacral Plexus (L4-S4)
What is the cervical plexus?
10+ nerves that innervate skin and muscles of the neck and shoulder
example:
Phrenic nerve – controls diaphragm
branches from C3,4,5 keeps the diaphragm “alive”
Fractures above the C3 level - respiratory arrest
Where is the brachial plexus? What does it innervate? Major nerves?
C5-T1 Innervates pectoral girdle and arms Convergences and divisions: Trunks Cords Branches major nerves: Musculocutaneous Median Axillary Radial Ulnar
What does the musculocutaneous nerve innervate?
supplies anterior arm - biceps brachii, coracobrachialis, brachialis muscles
skin of lateral forearm
What does the ulnar nerve innervate?
supplies some flexors of the forearm, medial hand, ½ ring finger to pinky
skin of medial palm, ½ ring finger to pinky
What does the median nerve innervate?
supplies most flexors of the forearm, lateral palm, thumb to ½ ring finger
skin of lateral palm, thumb to ½ ring finger
What does the radial nerve innervate?
posterior arm, posterior extensors of forearm
skin of posterior arm
What does the axillary nerve innervate?
supplies deltoid and teres minor muscles
skin of shoulder
What is carpal tunnel? What nerve is involved?
occurs when the connective tissue between the carpal bones and the flexor retinaculum becomes inflamed and compresses tendons and a nearby nerve Median nerve (brachial plexus)
What does the lumbar plexus innervate, in general? What are it’s major nerves?
Innervates lower abdominal, medial and anterior portions of the thigh
Femoral nerve
Obturator nerve
What does the femoral nerve innervate?
anterior, inferior, medial thigh skin sensation and anterior thigh muscles (quadriceps femoris, sartorius, iliopsoas)
What does the obturator nerve innervate?
medial thigh skin sensation and medial thigh muscles (adductors)
In general, what does the sacral plexus innervate?
skin and muscles of gluteal region, pelvis, perineum, posterior thigh, leg and foot
What doe the superior and inferior gluteal nerves innervate?
Superior Gluteal Nerve: gluteus medius, minimus and tensor fascia latae
Inferior Gluteal Nerve: gluteus maximus
What are the branches of the sciatic nerve?
Tibial Nerve: posterior thigh (all except biceps femoris short head), plantar and digital flexors of posterior leg and foot
Common Peroneal Nerve ( = Common Fibular Nerve): biceps femoris short head
Superficial Peroneal Nerve ( = Superficial Fibular Nerve): fibularis longus and brevis, skin of dorsum of foot
Deep Peroneal Nerve ( = Deep Fibular Nerve): anterior extensors (dorsiflexors) of leg and foot, skin between digit 1-2.
What does the pudental nerve innervate?
perineum, external anal sphincter, external urethral sphincter, skin of external genitalia
What is central cord syndrome?
compression of neurons within center of spinal cord
motor dysfunction, variable sensory loss, variable bladder function loss
common with cervical hyperextension
What is anterior spinal artery syndrome?
loss of blood flow to anterior 2/3 of spinal cord, ischemia, infarction
intervertebral disc herniation, fracture, blocked aortic blood flow
What is Brown-Sequard syndrome?
hemisection of the spinal cord, damage of ascending and descending tracts on one side of spinal cord
paralysis or loss of sensation, depending on specific pathways lesioned
What is conus medullaris syndrome?
injury to lower spinal cord, fractured L1/L2
urinary retention, erectile dysfunction, constipation, relaxed anal sphincter, loss of anal and bulbocavernosus reflex, inguinal sensation loss, motor weakness
What is cauda equina syndrome?
compression of bilateral nerve roots of lumbosacral region due to fracture of lumbar spine, sacrum, or acute herniated disc
motor and sensory loss variable, major sign is incontinence
